Systems, devices, and methods for multiple channel pulse width modulation dimming control

ABSTRACT

Systems, devices, and methods for adjusting the relative intensities of each of a plurality of waveband or color channel of light being produced. A constant current for each waveband channel is provided by a driver circuit to set a desired intensity value for that waveband channel. Separately, universal PWM is applied synchronously to each waveband channel simultaneously to set an overall lighting or dimming level.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 62/826,434, filed Mar. 29, 2019, U.S. Provisional Patent Application No. 62/826,445, filed Mar. 29, 2019, U.S. Provisional Patent Application No. 62/826,449, filed Mar. 29, 2019, and U.S. Provisional Patent Application No. 62/829,859, filed, Apr. 5, 2019, the entire content of each of which is hereby incorporated by reference.

FIELD

Embodiments described herein relate to diming control for light sources.

SUMMARY

Modern variable color luminaires including, for example, a plurality of LEDs, provide independent dimming of each group of LEDs (e.g., groups of LEDs corresponding to the same waveband). Dimming is achieved using pulse-width-modulation (“PWM”) or another similar modulation technique (e.g., pulse position modulation, bit pattern modulation, etc.). Due to the rapid ON and OFF times achieved with LEDs, each of these modulation methods causes some wavebands to be present (i.e., ON) and others absent (i.e., OFF) at a given time, dependent upon chosen dimming levels.

As illustrated in timing diagrams 400 in FIG. 4, for a given timeframe, TTOTAL, four wavebands of light can be driven differently, such that ON and OFF times are out of synchronization with one another. For example, a drive signal 405 for RED emitters can be set at an 80% duty cycle, a drive signal 410 for GREEN emitters can be set at a 60% duty cycle, a drive signal 415 for BLUE emitters can be set at a 20% duty cycle, and a drive signal 420 for ULTRAVIOLET emitters can be set to 90% duty cycle. As a result, during time T₁, all of the emitters are ON, during time T₂, some emitters are ON and others are OFF, and during time T₃, none of the emitters are ON. Although these variations in ON and OFF times are imperceptible to the human eye, such differences are significant enough to affect, for example, photobiological phenomena (e.g., photosynthesis) in plants. Optimal biological function would only result, for example, when all necessary component colors are present simultaneously. In time T₂, in FIG . 4, an incomplete spectrum of light is being produced (e.g., for illuminating a plant or crop).

Systems, devices, and methods are described herein for adjusting the relative intensities of each of a plurality of wavebands or color bands of light being produced. A constant forward current for each waveband channel is provided by a driver circuit to set a desired intensity value for that waveband channel. Separately, universal PWM is applied synchronously to each waveband or color channel simultaneously to set an overall lighting or dimming level. Conventionally, using forward currents to drive LEDs is undesirable because available forward currents are limited by a minimum forward current that is able to produce a desirable amount of output flux. This results in poor dimming resolution in systems which only control forward current. By separately controlling dimming independent of the forward current control, the problems associated with forward current dimming are eliminated.

Lighting fixtures described herein provide for multiple channel dimming control. The lighting fixtures include a plurality of arrays of light sources, a plurality of driver circuits, and a controller. Each of the plurality of arrays of light sources is configured to generate a light output. Each of the plurality of driver circuits is configured to drive one of the plurality of arrays of light sources. The controller includes a non-transitory computer readable medium and processing unit. The controller includes computer executable instructions stored in the computer readable medium for controlling operation of the lighting fixture to provide, by the controller, a respective drive signal to each of the plurality of respective driver circuits, generate, using each of the plurality of respective driver circuits, a respective constant current drive signal for a respective one of the plurality of arrays of light sources in response to the respective drive signal received from the controller, the respective constant current drive signal corresponding to an intensity for the respective one of the plurality of arrays of light sources, and provide, by the controller, a pulse-width modulation (“PWM”) signal to a switch for each of the plurality of respective drive circuits to set an overall dimming level for each of the plurality of arrays of light sources.

Systems described herein provide for multiple channel dimming control. The systems include a light fixture and a controller. The light fixture includes a plurality of arrays of light sources. Each of the plurality of arrays of light sources is configured to generate a light output. Each of the plurality of driver circuits is configured to drive one of the plurality of arrays of light sources. The controller includes a non-transitory computer readable medium and processing unit. The controller includes computer executable instructions stored in the computer readable medium for controlling operation of the system to provide, by the controller, a respective drive signal to each of the plurality of respective driver circuits, generate, using each of the plurality of respective driver circuits, a respective constant current drive signal for a respective one of the plurality of arrays of light sources in response to the respective drive signal received from the controller, the respective constant current drive signal corresponding to an intensity for the respective one of the plurality of arrays of light sources, and provide, by the controller, a pulse-width modulation (“PWM”) signal to a switch for each of the plurality of respective drive circuits to set an overall dimming level for each of the plurality of arrays of light sources.

Methods described herein provide for multiple channel dimming control. The methods include providing, by the controller, a respective drive signal to each of a plurality of respective driver circuits, generating, using each of the plurality of respective driver circuits, a respective constant current drive signal for a respective array of light sources in response to the respective drive signal, the respective constant current drive signal corresponding to an intensity for the respective array of light sources, and providing, by the controller, a pulse-width modulation (“PWM”) signal to a switch for each of the plurality of respective drive circuits to set an overall dimming level for each of the respective array of light sources.

Before any embodiments are explained in detail, it is to be understood that the embodiments are not limited in its application to the details of the configuration and arrangement of components set forth in the following description or illustrated in the accompanying drawings. The embodiments are capable of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings.

In addition, it should be understood that embodiments may include hardware, software, and electronic components or modules that, for purposes of discussion, may be illustrated and described as if the majority of the components were implemented solely in hardware. However, one of ordinary skill in the art, and based on a reading of this detailed description, would recognize that, in at least one embodiment, the electronic-based aspects may be implemented in software (e.g., stored on non-transitory computer-readable medium) executable by one or more processing units, such as a microprocessor and/or application specific integrated circuits (“ASICs”). As such, it should be noted that a plurality of hardware and software based devices, as well as a plurality of different structural components, may be utilized to implement the embodiments. For example, “servers” and “computing devices” described in the specification can include one or more processing units, one or more computer-readable medium modules, one or more input/output interfaces, and various connections (e.g., a system bus) connecting the components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a first lighting system.

FIG. 2 illustrates a second lighting system.

FIG. 3 illustrates a control system for implementing multiple channel pulse-width modulation (“PWM”) dimming control.

FIG. 4 illustrates PWM dimming control.

FIG. 5 illustrates multiple channel PWM dimming control.

FIG. 6 illustrates a method for multiple channel PWM dimming control.

DETAILED DESCRIPTION

FIG. 1 illustrates a first lighting system 100 that includes four light fixtures 105, 110, 115, and 120. Each of the fixtures 105-120 is connected to a controller 125 in a wired or wireless manner for receiving control signals that control respective light outputs 140, 145, 150, and 155 of the fixtures 105-120.

FIG. 2 illustrates a second lighting system 200 that includes four light fixtures 205, 210, 215, and 220. Each of the fixtures 205-220 includes its own internal controller for controlling respective light outputs 235, 240, 245, and 250 of the fixtures 205-220. The controllers internal to each of the fixtures 205-220 operate in a similar manner to the controller 125 in FIG. 1. An exemplary controller for the system 100 or fixtures 205-220 is described with respect to FIG. 3.

FIG. 3 illustrates a system 300 for controlling the outputs of a plurality of light sources (e.g., light sources corresponding to different wavebands of light). A controller 305 for the system 300 is electrically and/or communicatively connected to a variety of modules or components of the system 300. The controller 305 can correspond to, for example, the controller 125 of FIG. 1 or the internal controllers of the fixtures 205-220. For illustrative purposes, the controller 305 is shown as providing drive signals independently and discretely to a plurality of drivers 310 (e.g., driver [1] to driver [N]). The controller 305 is also connected to a user interface 315, and a power input circuit 320. The drivers 310 are each individually connected to an array of light sources 330 (e.g., one or more LEDs). In some embodiments, each array of light sources 330 is configured to generate a narrow-band light output (e.g., within a variance range of +/−10 nanometers of central emitter wavelength) corresponding to different wavelengths of light. For example, a first array of light sources can produce light corresponding to infrared light (e.g., wavelengths in the range of approximately 800 nanometers to 1 micrometer). A final array of light sources can produce light corresponding to ultraviolet light (e.g., wavelengths in the range of approximately 200 nanometers to 400 nanometers). In some embodiments, the system 300 includes at least ten arrays of light sources 330 (e.g., between 10 and 35 arrays of light sources 330). In other embodiments, the system 300 includes fewer than ten arrays of light sources 330. The arrays of light sources 330 can, for example, be spectrally evenly spaced with respect to one another (e.g., consistent wavelength gaps between arrays along the electromagnetic spectrum) or the arrays of light sources 330 can be spectrally unevenly spaced such that some arrays are closer to spectrally adjacent arrays than others.

The controller 305 includes combinations of hardware and software that are operable to, among other things, control the operation of the system 300, control the output of the arrays of light sources 330 (e.g., controlling output intensities of the light sources), etc. The controller 305 includes a plurality of electrical and electronic components that provide power, operational control, and protection to the components and modules within the controller 305 and/or the system 300. For example, the controller 305 includes, among other things, a processing unit 335 (e.g., a microprocessor, a microcontroller, an electronic process, an electronic controller, or another suitable programmable device), a memory 340, input units 345, and output units 350. The processing unit 335 includes, among other things, a control unit 355, an arithmetic logic unit (“ALU”) 360, and a plurality of registers 365 (shown as a group of registers in FIG. 3), and is implemented using a known computer architecture (e.g., a modified Harvard architecture, a von Neumann architecture, etc.). The processing unit 335, the memory 340, the input units 345, and the output units 350, as well as the various modules connected to the controller 305 are connected by one or more control and/or data buses (e.g., common bus 370). The control and/or data buses are shown generally in FIG. 3 for illustrative purposes.

The memory 340 is a non-transitory computer readable medium and includes, for example, a program storage area and a data storage area. The program storage area and the data storage area can include combinations of different types of memory, such as a ROM, a RAM (e.g., DRAM, SDRAM, etc.), EEPROM, flash memory, a hard disk, an SD card, or other suitable magnetic, optical, physical, or electronic memory devices. The processing unit 335 is connected to the memory 340 and executes software instructions that are capable of being stored in a RAM of the memory 340 (e.g., during execution), a ROM of the memory 340 (e.g., on a generally permanent basis), or another non-transitory computer readable medium such as another memory or a disc. Software included in the implementation of the system 300 can be stored in the memory 340 of the controller 305. The software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. The controller 305 is configured to retrieve from the memory 340 and execute, among other things, instructions related to the control processes and methods described herein. In other constructions, the controller 305 includes additional, fewer, or different components.

The user interface 315 is included to provide user input to the system 300 and controller 305. The user interface 315 is operably coupled to the controller 305 to control, for example, the output of the arrays of light sensors 330, etc. The user interface 315 can include any combination of digital and analog input devices required to achieve a desired level of control for the system 300. For example, the user interface 315 can include a computer having a display and input devices, a touch-screen display, a plurality of knobs, dials, switches, buttons, faders, or the like.

The power input circuit 320 supplies a nominal AC or DC voltage to the system 300 and components within the system 300. The power input circuit 320 can be powered by mains power having nominal line voltages between, for example, 100V and 240V AC and frequencies of approximately 50-60 Hz. The power input circuit 320 is also configured to supply lower voltages to operate circuits and components within the system 300 (e.g., controller 305). Additionally or alternatively, the system 300 can receive power from one or more batteries or battery packs.

The controller 305 is configured to provide drive signals to the drivers 310 for each of the arrays of light sources 330. Based on the provided drive signals, each of the drivers 310 generates a constant current drive signal corresponding to a desired intensity for its respective waveband of light. The controller 305 separately and independently then controls a respective switch (e.g., a field-effect transistor [“FET”]) 375 for each array of light sources 330 using the same PWM signal in parallel. By regulating the outputs of the drivers 310 in such a manner, the controller 305 is able to control the outputs of the arrays of light sources 330 (i.e., dimming) such that each is producing light at the same time (i.e., light sources are ON at the same time and OFF at the same time). In some embodiments, synchronization having a resolution of approximately 10 microseconds or less is achieved.

As illustrated in timing diagrams 500 in FIG. 5, for a given timeframe, T_(TOTAL), four wavebands of light are driven synchronously, such that ON and OFF times for each waveband of light are ON at the same time and OFF at the same time. As shown in FIG. 5, each of, for example, a drive signal 505 for RED emitters, a drive signal 510 for GREEN emitters, a drive signal 515 for BLUE emitters, and a drive signal 520 for ULTRAVIOLET emitters can be set to the same duty cycle. With respect to embodiments where an object being illuminated is a plant or crop, optimal biological function would result from all necessary component colors being presented simultaneously.

A method 600 for multiple channel PWM dimming control is illustrated in FIG. 6. The method 600 may be performed using, for example, the system 300 and controller 305 described above. The method 600 includes the controller 305 providing a respective drive signal to each of a plurality of respective driver circuits 310 (STEP 605). Each respective driver circuit 310 then generates a constant current drive signal in response to the respect drive signal it received from the controller 305 (STEP 610). The constant current drive signal corresponds to an intensity for a respective plurality of light sources being driven by the respective driver circuits 310. The controller 305 then provides a universal pulse-width modulation (“PWM”) signal synchronously to a switch for each of the plurality of respective drive circuits to set an overall dimming level for each of the respective pluralities of light sources (STEP 615). The switches (e.g., FETs) are used to control a duty cycle (i.e., ON-time and OFF-time) of the constant current drive signal simultaneously and consistently for each of the respective driver circuits 310 to achieve uniform PWM dimming among the different wavebands or color channels. In some embodiments, the duty cycle of the universal PWM signal is controlled through the user interface 315. In some embodiments, the intensity of the output of individual pluralities of light sources are also controlled through the user interface 315 (e.g., to achieve independent intensity levels for each plurality of light sources).

Thus, embodiments described herein provide, among other things, systems, devices, and methods for implementing multiple channel PWM dimming control. 

What is claimed is:
 1. A lighting fixture configured for multiple channel dimming control, the lighting fixture comprising: a plurality of arrays of light sources, each of the plurality of arrays of light sources configured to generate a light output; a plurality of driver circuits, each of the plurality of driver circuits configured to drive one of the plurality of arrays of light sources; and a controller including a non-transitory computer readable medium and processing unit, the controller including computer executable instructions stored in the computer readable medium for controlling operation of the lighting fixture to: provide, by the controller, a respective drive signal to each of the plurality of respective driver circuits, generate, using each of the plurality of respective driver circuits, a respective constant current drive signal for a respective one of the plurality of arrays of light sources in response to the respective drive signal received from the controller, the respective constant current drive signal corresponding to an intensity for the respective one of the plurality of arrays of light sources, and provide, by the controller, a pulse-width modulation (“PWM”) signal to a switch for each of the plurality of respective drive circuits to set an overall dimming level for each of the plurality of arrays of light sources.
 2. The lighting fixture of claim 1, wherein the light sources are light emitting diodes.
 3. The lighting fixture of claim 1, wherein the plurality of arrays of light sources includes a first array of light sources configured to produce infrared light.
 4. The lighting fixture of claim 3, wherein the plurality of arrays of light sources includes a second array of light sources configured produce ultraviolet light.
 5. The lighting fixture of claim 4, wherein the plurality of arrays of light sources includes at least ten arrays of light sources.
 6. The lighting fixture of claim 4, wherein the plurality of arrays of light sources includes fewer than ten arrays of light sources.
 7. The lighting fixture of claim 4, wherein the plurality of arrays of light sources are spectrally evenly spaced with respect to one another along the electromagnetic spectrum.
 8. The lighting fixture of claim 1, wherein the PWM signal is provided synchronously to the switch for each of the plurality of respective drive circuits.
 9. A system for multiple channel dimming control, the system comprising: a light fixture configured to produce a light output, the light fixture including: a plurality of arrays of light sources, each of the plurality of arrays of light sources configured to generate a light output, and a plurality of driver circuits, each of the plurality of driver circuits configured to drive one of the plurality of arrays of light sources; and a controller including a non-transitory computer readable medium and processing unit, the controller including computer executable instructions stored in the computer readable medium for controlling operation of the system to: provide, by the controller, a respective drive signal to each of the plurality of respective driver circuits, generate, using each of the plurality of respective driver circuits, a respective constant current drive signal for a respective one of the plurality of arrays of light sources in response to the respective drive signal received from the controller, the respective constant current drive signal corresponding to an intensity for the respective one of the plurality of arrays of light sources, and provide, by the controller, a pulse-width modulation (“PWM”) signal to a switch for each of the plurality of respective drive circuits to set an overall dimming level for each of the plurality of arrays of light sources.
 10. The system of claim 9, wherein the light sources are light emitting diodes.
 11. The system of claim 9, wherein the plurality of arrays of light sources includes a first array of light sources configured to produce infrared light.
 12. The system of claim 11, wherein the plurality of arrays of light sources includes a second array of light sources configured produce ultraviolet light.
 13. The lighting system of claim 12, wherein the plurality of arrays of light sources includes at least ten arrays of light sources.
 14. The lighting system of claim 12, wherein the plurality of arrays of light sources includes fewer than ten arrays of light sources.
 15. The lighting system of claim 12, wherein the plurality of arrays of light sources are spectrally evenly spaced with respect to one another along the electromagnetic spectrum.
 16. The lighting system of claim 9, wherein the PWM signal is provided synchronously to the switch for each of the plurality of respective drive circuits.
 17. A method for multiple channel dimming control, the method comprising: providing, by the controller, a respective drive signal to each of a plurality of respective driver circuits, generating, using each of the plurality of respective driver circuits, a respective constant current drive signal for a respective array of light sources in response to the respective drive signal, the respective constant current drive signal corresponding to an intensity for the respective array of light sources, and providing, by the controller, a pulse-width modulation (“PWM”) signal to a switch for each of the plurality of respective drive circuits to set an overall dimming level for each of the respective array of light sources.
 18. The method of claim 17, wherein the switch is a field-effect transistor (“FET”).
 19. The method of claim 17, further comprising receiving, from a user interface, a first user input related to the overall dimming level.
 20. The method of claim 19, further comprising receiving, from the user interface, a second user input related to the intensity for the respective array of light sources. 